Non-flammable solvate ionic liquid electrolyte with diluters

Abstract

An electrolyte composition is provided. The electrolyte composition includes a solvate ionic liquid having an anion and a complex of an ether and a cation, and a diluter including a phosphorus-containing flame-retardant having a dielectric constant of less than or equal to about 20.

What is claimed is: 
     
         1 . An electrolyte composition comprising:
 a solvate ionic liquid having an anion and a complex comprising an ether and a cation; and   a diluter comprising a phosphorus-containing flame-retardant having a dielectric constant of less than or equal to about 20.   
     
     
         2 . The electrolyte composition according to  claim 1 , wherein the anion of the solvate ionic liquid is selected from the group consisting of bis(trifluoromethanesulfonyl)imide (TFSI − ), bis(pentafluoroethanesulfonyl)imide (BETI − ), hexafluorophosphate (PF 6   − ), tetrafluoroborate (BF 4   − ), trifluoromethyl sulfonate (TfO − ), difluoroborate (DFOB − ), bis(oxalate)borate (BOB − ), and a combination thereof. 
     
     
         3 . The electrolyte composition according to  claim 1 , wherein the ether is an oligoether having the formula CH 3 O—(CH 2 CH 2 O) n —CH 3 , where 1≤n≤10 and the cation is Li + . 
     
     
         4 . The electrolyte composition according to  claim 1 , wherein the diluter comprises a phosphate flame-retardant selected from the group consisting of triethyl phosphate, trimethyl phosphate, tributyl phosphate, triphenyl phosphate, phosphazene, diphenyloctyl phosphate, tris(2, 2, 2-trifluoroethyl)phosphate, and a combination thereof. 
     
     
         5 . The electrolyte composition according to  claim 1 , wherein the diluter comprises a phosphite flame-retardant selected from the group consisting of triethyl phosphite, trimethyl phosphite, tributyl phosphite, triphenyl phosphite, and a combination thereof. 
     
     
         6 . The electrolyte composition according to  claim 1 , wherein the diluter comprises a phosphonate flame-retardant selected from the group consisting of bis(2.2.2.-trifluoroethyl) methyl phosphonate, diethyl phosphonate, diethyl ethyl phosphonate, and a combination thereof. 
     
     
         7 . The electrolyte composition according to  claim 1 , wherein the solvate ionic liquid and the diluter are present in a solvate ionic liquid:diluter ratio of from about 1:10 to about 5:1 by volume. 
     
     
         8 . The electrolyte composition according to  claim 1 , wherein the solvate ionic liquid comprises an anion:complex molar ratio of about 1:1. 
     
     
         9 . The electrolyte composition according to  claim 1 , further comprising:
 a solid electrolyte interface additive.   
     
     
         10 . The electrolyte composition according to  claim 1 , wherein the electrolyte composition is substantially free of solvents that are not ionic liquids or solvate ionic liquids. 
     
     
         11 . The electrolyte composition according to  claim 1 , wherein the solvate ionic liquid and diluter are embedded within a polymer, the polymer having a concentration of greater than 0 wt. % to less than or equal to about 50 wt. % based on the total weight of the solvate ionic liquid and the polymer, and wherein the electrolyte composition is a gel electrolyte. 
     
     
         12 . An electrochemical cell comprising the electrolyte composition according to  claim 1 . 
     
     
         13 . An electrochemical cell comprising:
 a positive electrode comprising positive electroactive particles;   a negative electrode comprising negative electroactive particles; and   and an electrolyte composition comprising:
 a solvate ionic liquid having an anion and a glyme-lithium cation complex in an anion:glyme-lithium cation complex molar ratio of about 1:1, and 
 a diluter comprising a phosphorus-containing flame-retardant having a dielectric constant of less than or equal to about 20, 
 wherein the solvate ionic liquid and the diluter are present in a solvate ionic liquid:diluter volumetric ratio of from about 1:10 to about 5:1, and 
 wherein the electrolyte composition is non-flammable, 
   wherein the electrochemical cell exhibits a capacity retention of greater than or equal to about 95% after 100 cycles of charging and discharging.   
     
     
         14 . The electrochemical cell according to  claim 13 , wherein the anion of the solvate ionic liquid is bis(trifluoromethanesulfonyl)imide (TFSI − ), bis(pentafluoroethanesulfonyl)imide (BETI − ), hexafluorophosphate (PF 6   − ), tetrafluoroborate (BF 4   − ), trifluoromethyl sulfonate (TfO − ), difluoroborate (DFOB − ), bis(oxalate)borate (BOB − ), or a combination thereof, and the glyme of the solvate ionic liquid is ethylene glycol dimethyl ether (G1), diethylene glycol dimethyl ether (G2), triethylene glycol dimethyl ether (G3), tetraethylene glycol dimethyl ether (G4), or a combination thereof. 
     
     
         15 . The electrochemical cell according to  claim 13 , wherein the anion is bis(trifluoromethanesulfonyl)imide (TFSI − ), the glyme comprises at least one of triethylene glycol dimethyl ether (G3) or tetraethylene glycol dimethyl ether (G4), and the diluter comprises triethyl phosphate. 
     
     
         16 . The electrochemical cell according to  claim 13 , wherein the electrochemical cell further comprises a polymeric separator disposed between the positive electrode and the negative electrode, wherein the electrolyte composition is capable of transporting lithium ions between the positive electrode and the negative electrode, and wherein the electrolyte composition is a liquid or a gel comprising the solvate ionic liquid and the diluter embedded within a polymer matrix. 
     
     
         17 . The electrochemical cell according to  claim 13 , wherein the electrochemical cell is a solid-state electrochemical cell further comprising a solid-state electrolyte disposed between the positive electrode and the negative electrode, wherein the electrolyte composition is in contact with at least a portion of the positive electroactive particles, the negative electroactive particles, the solid-state electrolyte, or a combination thereof, and wherein the electrolyte composition is a liquid or a gel comprising the solvate ionic liquid and the diluter embedded within a polymer matrix. 
     
     
         18 . A method of fabricating an electrochemical cell, the method comprising:
 contacting an electrolyte composition to at least one of a positive electrode, a negative electrode, or one of a polymeric separator or a solid-state electrolyte,   wherein the electrolyte composition comprises:
 a solvate ionic liquid having an anion and a complex comprising an ether and a cation; and 
 a diluter comprising a phosphorus-containing flame-retardant having a dielectric constant of less than or equal to about 20. 
   
     
     
         19 . The method according to  claim 18 , wherein the electrolyte composition is a liquid or a gel comprising the solvate ionic liquid and the diluter embedded within a polymer matrix. 
     
     
         20 . The method according to  claim 18 , wherein the anion of the solvate ionic liquid is bis(trifluoromethanesulfonyl)imide (TFSI − ), bis(pentafluoroethanesulfonyl)imide (BETI − ), hexafluorophosphate (PF 6   − ), tetrafluoroborate (BF 4   − ), trifluoromethyl sulfonate (TfO − ), difluoroborate (DFOB − ), bis(oxalate)borate (BOB − ), or a combination thereof; the glyme of the solvate ionic liquid is ethylene glycol dimethyl ether (G1), diethylene glycol dimethyl ether (G2), triethylene glycol dimethyl ether (G3), tetraethylene glycol dimethyl ether (G4), or a combination thereof; and the cation is lithium cation.